Th17 cells are central mediators in chronic inflammatory processes and principal pathogenic effectors in several types of autoimmunity conditions previously thought to be Th1-mediated (Weaver T. et al. (2008) Annu. Rev. Immunol., 25, p. 821-852). The pro-inflammatory cytokine IL-17 is mainly expressed by Th17 cells and is present at elevated levels in synovial fluid of patients with rheumatoid arthritis (RA) and has been shown to be involved in early RA development. In addition, IL-17 is a potent inducer of TNF-alpha and IL-1, the latter being mainly responsible for bone erosion and the very painful consequences for affected patients (Lubberts E. (2008) Cytokine, 41, p. 84-91). Furthermore, inappropriate or excessive production of IL-17 is associated with the pathology of various other diseases and disorders, such as osteoarthritis, loosening of bone implants, acute transplant rejection (Antonysamy et al., (1999) J. Immunol, 162, p. 577-584; van Kooten et al. (1998) J. Am. Soc. Nephrol., 9, p. 1526-1534), septicemia, septic or endotoxic shock, allergies, asthma (Molet et al. (2001) J. Allergy Clin. Immunol., 108, p. 430-438), bone loss, psoriasis (Teunissen et al. (1998) J. Invest. Dermatol, 111, p. 645-649), ischemia, systemic sclerosis (Kurasawa et al. (2000) Arthritis Rheum., 43, p. 2455-2463), stroke, and other inflammatory disorders. Consequently, a need exists for therapies that modulate the biological activities of IL-17.
Early neutralization of endogenous IL-17 by an IL-17 receptor-IgG1-Fc fusion protein starting after the immunization protocol during the initial phase of arthritis suppresses the onset of experimental arthritis (Lubberts et al. (2001) J. Immunol., 167, p. 1004-1013). Moreover, treatment with a neutralizing anti-IL-17 antibody in an animal model after the onset of collagen-induced arthritis reduced joint inflammation, cartilage destruction and bone erosion (Lubberts et al. (2004) Arthritis and Rheumatism, 50; 650-659). Histological analysis confirmed the suppression of joint inflammation, and systemic IL-6 levels were significantly decreased after treatment with an anti-IL-17 antibody. In contrast, systemic as well as local IL-17 overexpression using an adenoviral vector expressing murine IL-17 accelerated the onset of collagen-induced arthritis (CIA) and aggravated synovial inflammation at the site (Lubberts et al. (2001) J. Immunol., 167, p. 1004-1013 and Lubberts et al. (2002), Inflamm. Res. 51, p 102-104). More recently it could be demonstrated that the use of anti-IL-17 antibodies improved the clinical symptoms of psoriasis, rheumatoid arthritis and non-infectious uveitis (Leonardi C. et al. (2012) N. Engl. J. Med. 366, p. 1190-1199; Hueber W. et al. (2010) Sci Transl Med. 2(52):52ra72).
Interleukin 6 (IL-6) is a potent cytokine that regulates cell growth and differentiation, and is also an important mediator of acute inflammatory responses. IL-6 acts via a receptor complex consisting of a specific IL-6 receptor (IL-6R) and a signal transducing subunit (gp130). Dysregulated IL-6 signaling has been implicated in the pathogenesis of many diseases, such as multiple myeloma, autoimmune diseases and prostate cancer. Accordingly, there exists a need for therapies that modulate the biological activities of IL-6 and/or IL-6R.